Severe Thunderstorm Warning 1, NWS Medford, OR

778 
WWUS56 KMFR 152231
SVSMFR

Severe Weather Statement
National Weather Service Medford OR
231 PM PST Wed Jan 15 2020

ORC011-015-152240-
/O.EXP.KMFR.SV.W.0001.000000T0000Z-200115T2230Z/
Curry OR-Coos OR-
231 PM PST Wed Jan 15 2020

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN CURRY AND
SOUTHWESTERN COOS COUNTIES HAS EXPIRED...
    
The severe thunderstorm which prompted the warning has weakened. 
Therefore, the warning has been allowed to expire. Continued strong 
southerly winds are expected to continue this afternoon.

LAT...LON 4299 12458 4316 12444 4292 12399 4260 12450
      4261 12450 4266 12456
TIME...MOT...LOC 2230Z 215DEG 50KT 4309 12429 

$$

SVEN

Area Forecast Discussion...CORRECTED
National Weather Service Medford OR
847 AM PST Wed Jan 15 2020

.Corrected tide height in Marine discussion.

.DISCUSSION...14/12Z NAM in. 14/12Z GFS in through 180hr.

...and the hits just keep on coming...

An upper trough is digging offshore due to short waves digging
down the back side of it. This trough will support a strong
surface front which will move onshore later today. The 15/12Z NAM
(15/06Z GFS) run shows a peak OTH-ACV gradient of -9.2(-10.0) mb
at 1 PM(1 PM) PST Wednesday and a peak MFR-RDD gradient of
-9.4(-10.0) at 1 PM(4 PM) PST Wednesday. These have trended up
 from yesterday and both will likely support High Wind Warning
 winds along the coast and in the Shasta Valley, respectively, and
 the east side will see high winds as well.

This system will bring moderate to heavy snows across southern
Oregon and northern California. The heaviest snows will be in
northern California in the Marble Mountains as well as for the Mt.
Shasta Area where up to 20 inches of snow could fall in 24 hours.
Additionally, more moderate amounts of snow could fall in the
Cascades, Siskiyous, Douglas County Foothills, and the Klamath
Basin. Winter Weather Advisories exist for these areas. Snow
levels will generally be 2500 to 3000 feet, but in Siskiyou County,
due to the south winds, they will be closer to 2000 feet. Please
see the WSWMFR for more details on snow hazards. Additionally,
heavy snow is expected in the Kalmiopsis Wilderness, and possibly
in the adjacent Illinois valley if cold air gets trapped there.
The heavy snow will impact travel, combine with wind to create
limited visibilities and possibly cause power outages.

Once the front moves inland there will be plenty of post-frontal
shower activity as the upper trough will remain just offshore
Wednesday night into Thursday. Snow levels will drop to around
2000 feet MSL this evening behind the front, and remain near that
level into Thursday morning.

The upper trough will finally move inland Thursday night and
ridge will build in from the south. That will provide a relative
break in the action, but there will still be some light shower
activity over the area. Snow levels will drop back down to around
1000 feet MSL Friday morning. The break will end Saturday, when an
incoming upper level trough will drive another front will move
onshore. That will bring another round of strong winds and
precipitation, but the ensuing ridge will build in quickly, and
post frontal showers will diminish Saturday night.

&&

.AVIATION...For the 15/12Z TAF Cycle....Wind speed shear will be the
main hazard today into this evening. The morning sounding at Medford
shows stronger winds aloft and they will only increase over time.
These stronger winds are expected to mix down near and at the
surface late this morning through this evening, but winds aloft will
also be significant enough to keep wind speed shear in the forecast.

LIFR ceilings and visibilities have set up at Roseburg and Klamath
Falls. This should last into at least the mid morning hours, then
break up as stronger winds aloft begin to surface. The timing of
improving conditions at Roseburg and Klamath Falls could end up
being an hour or two earlier than what's in the TAF's, so watch for
updates.

Meanwhile Medford will hover between MVFR and IFR until at least mid
morning, but they could also see improving ceilings earlier than
what's indicated in the TAF.

Ceilings will lower again as precipitation moves into the area with
MVFR ceilings and occasional reduction in visibility in heavier
precipitation west of the Cascades. Klamath Falls should remain VFR
for the rest of the TAF period once the low clouds and fog break up.
-Petrucelli

&&

.MARINE...Corrected 845 AM PST Wednesday 15 Jan 2020...A series
of strong fronts will result in high to very high and steep to
very steep seas through the week.

The first of two strong fronts will impact the waters this morning.
South winds will only increase over time with gales and storm force
winds likely by mid morning. Storm force winds are only expected for
about a 9 hour period due to a low level coastal jet forming from
Gold beach northward. With wind waves near 20 feet combining with a
high tide of near 7 feet, this may bring waves into the parking
lot at Port Orford, and into the first row of the RV park at the
beach in Brookings/Harbor.

Once the front pushes onshore early this evening, winds will
diminish below storm force but gales are still expected to last
through this evening. Winds will continue to diminish below gales
overnight tonight, but hazardous seas conditions are still expected
due to a combination of an increasing west swell and there is a
chance for a brief period of fresh south swell from the wind waves
that were generated ahead of todays front. Please see MWWMFR for
details on all of the hazards.

Calmer winds are expected Thursday, but seas are still likely to be
high enough to warrant at least small craft conditions, but decided
not to issue at this time due to already occurring multiple
headlines.

Another strong front is expected to impact the waters Friday
afternoon through Friday night and could bring another round of gale
force winds and hazardous seas warning conditions.

An active pattern will continue next weekend, but there is some
evidence winds and seas won't be as high. -Petrucelli/Sven

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning from 1 PM this afternoon to 4 PM PST Thursday
        for ORZ030-031.
     Winter Weather Advisory from 4 PM this afternoon to 4 PM PST
        Thursday for ORZ025-027>030.
     Wind Advisory from 1 PM this afternoon to 4 PM PST Thursday for
        ORZ030-031.
     High Wind Warning until 7 PM PST this evening for ORZ021-022.
     Wind Advisory until 10 PM PST this evening for ORZ026.

CA...High Wind Warning from 1 PM this afternoon to 4 PM PST Thursday
        for CAZ085.
     Wind Advisory from 1 PM this afternoon to 4 PM PST Thursday for
        CAZ085.
     Winter Storm Warning from 4 PM this afternoon to 4 PM PST
     Thursday above 2000 feet in the for CAZ080.
     Winter Storm Warning from 4 PM this afternoon to 4 PM PST
        Thursday for CAZ082-083.
     Winter Weather Advisory from 4 PM this afternoon to 4 PM PST
     Thursday above 2000 feet in the for CAZ080-081.
     High Wind Warning until 4 AM PST Thursday for CAZ081.
     Winter Weather Advisory from 4 PM this afternoon to 4 PM PST
        Thursday for CAZ083.

Pacific Coastal Waters...Storm Warning until 4 PM PST this afternoon
        for PZZ350-356-370-376.
     Gale Warning until 10 PM PST this evening for
        PZZ350-356-370-376.
     Hazardous Seas Warning from 10 PM this evening to 4 AM PST
        Thursday for PZZ350-356-370-376.

15/18/04